A catholic order of nuns admitted on Tuesday emotional abuse and neglect took place in its residential homes in Northern Ireland.

The Sisters of Nazareth have already acknowledged and apologised for physical and sexual attacks which occurred within their properties, a focus of the UK’s largest ever institutional child abuse public inquiry.

A senior member, speaking on behalf of the congregation, said evidence from victims at the Derry homes was “shocking and harrowing”.

Sister Brenda McCall added: “We must accept that at certain times, by certain sisters, things were just not right.”

The treatment of young people – orphaned or taken away from their unmarried mothers – in houses run by nuns, brothers or the State is a key concern of an investigation chaired by retired High Court judge Sir Anthony Hart.

The probe, being held in Banbridge, Co Down, is considering cases between 1922 and 1995.

Sr Brenda said the congregation accepted that sisters, older boys and lay people who accessed the homes physically assaulted children. She added bullying would have occurred.

The nun said: “There have been individuals apologised to if they came forward.

“I would like to say, having been up at the back [of the inquiry] for the last few weeks, it was a very harrowing and challenging time for us as a congregation to listen to the evidence.

“We are a human group. We had people who were champions of the cause and we had people that were a bit weaker. We had some wonderful, heroic, I would say inspirational sisters.

“I am proud to stand on their shoulders and carry on the work of the congregation started by our founder, Victoire Larmenier, to work for the weak of society.”

Later on Tuesday former Catholic bishop Edward Daly, 81, expressed admiration for the Sisters of Nazareth nuns.

He said in 36 years of ministry he only heard one complaint, from a woman separated from her brothers as a child and sent from a home to Australia.

Dr Daly added: “They were doing work that needed to be done, that nobody else was doing.”

The bishop, who was ordained in 1974, said: “It was a culture shock, I had never before experienced poverty of that nature.

“Housing was such an abominable standard, overcrowding and all the attendant things that went with that, it was quite shocking frankly.

“We all took the sisters for granted. The sisters were there, we knew they [children] were being cared for. We are all responsible for not knowing but I was surprised that so few sisters were involved and they looked after 5,000 children.

“One wonders what would have happened to those kids had the sisters not been there.

“I had complete faith in the sisters and I had no reason to believe otherwise than that they were doing excellent work.”